I will try to post my feelings and thoughts in as respectful a way as possible.
IMHO the people who have given the most curiously conflicting and/or .... I don't know... strange statements that have thrown things either off hte most, or off on tangents the most, seem to be from the people most close to him (brother, girlfriend).... like the stuff about stopping at the apartment for a backpack randomly being added into the mix, the cellphone ping in NWA being thrown into things almost like a deliberate wild goose chase, the fact nobody will comment on the cat and in fact almost seem to be avoiding the questions about it, or brushing it off, the NAMUS info being updated only after repeated prompting, the fursona name and animal being wrong, the weird conversations about him having a cat carrier but it being missing, then no wait he might not have ever had one after all, the suggestions he was at this airport, no wait he was at that airport (I mean seriously is there any evidence from anyone other than his brother's say-so that he ever even returned from NYC?) the license plate(S) conflicting info (OK only has one plate and it goes on the back so WTF is this about a front plate being removed and stuck inside the car behind the drivers' seat? Tho this came from LE so is less of a good example of what I'm illustrating, I know) etc etc etc etc
In light of all that, If I was a VERY suspicious person, I'd have to suspect that he disappeared voluntarily and the people closest to him are the only ones who know and they're helping by intentionally interfering with an investigation.
But that doesn't quite sit right with me so I am not willing to say that is my theory at this time... but if someone else said it was theirs, I'd surely understand where they were coming from.
JMO IMHO AND SO ON